Archive for May, 2012

Back as far as 2005, Mark Purdey (from Elworthy near Taunton in Somerset farming country) formulated the hypothesis that the routine over-usage of a veterinary medicine called levamisole to treat episodes of parasitic worm infections in cattle reduced the animals ability to use its immune system to defend itself against the bovine TB infection.

When cattle become infected with the bovine TB infection, their mammalian biosystem expresses an iron binding exocrine protein, lactoferrin, which scavenges and competes for free iron, thereby starving the parasite of its vital iron supply. In other words, their natural immune system tries to starve the parasite of iron, which effectively kills the parasite

Mark Purdy’s hypothesis stated that the use of this routine use of this medication, significantly affected the production of iron-based molecules, which caused a large reduction in the animal’s main line of defence against a TB infection. This was combined with the belief that dairy cattle are ingesting increasing amounts of iron in their diet.

Here we are in 2012 and we find another scientific journal publishing another paper which shows that cattle infected with fasiola hepatica (i.e. a parasitic worm infection) is strongly associated with the failure to detect bovine TB infections in cattle. See http://www.nature.com/ncomms/journal/v3/n5/full/ncomms1840.html

This large scale study (involving 3026 dairy herds) showed that there is a significant negative association between exposure to the fasciola hepatica parasite; and the ability of the intradermal comparative cervical tuberculin test used to diagnose bTB. The papers shows that cattle exposed to the parasite are between 27% and 38% less likely to provide an accurate TB test result.

Badgerland’s Thoughts

Perhaps it’s just me thinking on simplistic lines, but giving cattle lots of CLEAN water to drink and avoiding over-medicating them, might be a very good way to stop them getting parasitic worm infections, which might make it more likely they provide an accurate TB test result (allowing TB-infected animals to be culled out of the herds before they infect other animals).

In the meantime, might I suggest that beefeaters might like to choose meat from organically raised cattle which tend to have less need for medication and less intensively used water supplies.